The 2005 revision of the Energy Conservation Act introduced new and reinforced labeling provisions for appliances. The label must contain information on the appliance's expected electricity cost or fuel usage information. The new comparative rating system is presented as five-star rating, and provides consumers with the information needed to compare across products in the same category. Efficiency increases with the number of stars. As of May 2009, fuel or electricity cost information is now required for four designated products: air conditioners, electric refrigerators, electric toilet seats and TV sets. Use of labels indicating energy efficiency levels for other appliances are to be provided on a voluntary basis. However the revised Energy Conservation Act makes it necessary for retailers to make efforts to provide information concerning energy conservation features of products. Certain products have labels indicating both energy conservation standard achievement and expected annual electricity bill and annual fuel usage (Electric freezers, lights, electric toilet seats, gas cooking appliances, gas and oil water heaters). Computers, magnetic disk units, space heaters and transformers can be labeled according to energy conservation standard, while electric rice cookers, microwave ovens, video cassette and DVD recorders are covered by expected annual electricity bill and annual fuel usage labels. The latest revision was made on the evaluation criteria for standards of air conditioners, electric refrigerators, electric toilet seats and LC plasma TV sets. This took effect on April 1, 2011.